“Wireless computing” is a term that has come to describe wireless communications between computing devices or between a computer and peripheral devices such as printers. For example, many computers, including tower and laptop models, have a wireless communications card that comprises a transmitter and receiver connected to an antenna. Or alternatively, a Host Wire Adapter (HWA) is connected to the computer by a USB (Universal Serial Bus) cable. The HWA has an RF (Radio Frequency) transmitter and receiver capable of communicating data in a USB-cognizable format. This enables the computer to communicate by RF transmission with a wireless network of computers and peripheral devices. The flexibility and mobility that wireless computing affords is a major reason for its commercial success.
In wireless applications where directed transmitted beam (or controlled angle of radiation) is desired, multiple-antennas can be used, together with delay elements or phase shifters in multiple TX paths, to form the required beam. Phase-shifting the local oscillator (LO) signal between multiple TX paths or Cartesian combining of multiple TX paths has been used in implementing phased-array systems, with the limitation of narrow-band operation. However, when the data rate is high, the error vector magnitude (EVM) increases.